Embodiments of the invention relate to a method and device for controlling a motor vehicle towing a trailer.
Stability is a concern for a vehicle towing a trailer, especially when the towing vehicle is traveling at high speed or making a turn. Since the trailer significantly affects the dynamics of the towing vehicle, many control systems use techniques to improve the stability of the towing vehicle. For example, systems such as anti-lock braking systems (“ABS”), traction control systems (“TCS”), and vehicle dynamics control (“VDC”) systems can be configured to perform different functions for the vehicle to improve stability.
Existing methods and systems for dampening trailer oscillations or improving stability generally require applying symmetric braking or torque by, through, or to the towing vehicle, followed by asymmetric braking or torque (again by, through, or to the towing vehicle) when the trailer oscillations are higher than a threshold. When these control methods and systems apply symmetric torque at an inappropriate time, the trailer can oscillate more. On the other hand, these control methods and systems typically start delivering the asymmetric torque to dampen oscillations when the trailer oscillates under certain circumstances. For example, some methods and systems will wait for a period of time after the trailer oscillation has reached a frequency threshold in order to deliver any symmetric or asymmetric torque. In other words, these control methods and systems allow the trailer to oscillate as long as the oscillations occur below the threshold. During this time, however, the oscillations can become severe and excessively damaging particularly when the towing vehicle is traveling at high speed.